There is a need for non-invasive inspection and sampling of persons, articles of clothing, buildings, furnishings, vehicles, baggage, packages, mail, and the like for contaminating residues that may indicate chemical, radiological, biological or infectious hazards. Applications involve detection of trace materials, both particles and vapors, associated with persons who have handled explosives, detection of toxins in mail, or detection of spores on surfaces, while not limited thereto.
Current methods for environmental sampling often involve contacting use of swabs or liquids to obtain samples that are indicative of the composition of the environmental material of interest, but methods for sampling by “sniffing” are preferred. To inspect mail or luggage for example, the sampling method of U.S. Pat. No. 6,887,710 involves first placing the article or articles in a box-like enclosure equipped with airlocks, directing a blast of air onto the exposed surfaces in order to dislodge particles associated with the articles, then sampling the gaseous contents of the box by drawing any resulting aerosol through a sampling port. A similar approach for sampling persons is seen in U.S. Pat. No. 6,073,499 to Settles. Because any dislodged particles become dispersed in the larger enclosing space, very large volumes of air must be sampled in order to confidently ensure capture and analysis of any dislodged particles, and the process is inherently slow because each article or person must be moved into the box or chamber and the box sealed before sampling, an obvious disadvantage when large numbers of articles or persons must be screened, or when the articles are larger than can be reasonably enclosed, such as a truck, shipping container, or the hallway surfaces of a building.
Another technology is based on the luminescence of certain compounds when they attach to electron-rich explosive particles, and has been improved with the introduction of amplifying fluorescent polymers as described in U.S. Pat. No. 7,208,122 to Swager (ICx Technologies, Arlington Va.). Typically vapors are introduced into a tubular sensor lined with a conductive fluorescent polymer by suction. However, the suction intake inherently draws in air that has not contacted the article or surface of interest, even when held very close while sampling, and no provision is made for resuspending particles or vapor residues associated with the target surface. Furthermore, these sensors also lack a pre-concentrator and work only for analytes with electron-donating properties.
Another common analytical instrument for detection of nitrate-type explosives relies on pyrolysis followed by redox (electron capture) detection of NO2 groups (Scientrex EVD 3000), but is prone to false alarms. Ion mobility spectroscopic (IMS) detectors are in widespread use and typically have picogram sensitivity. IMS also requires the ionization of the sample, which is typically accomplished by a radioactive source such as Nickel-63 or Americium-241. This technology is found in most commercially available explosive detectors like the GE VaporTracer (GESecurity, Bradenton, Fla.), the Sabre 4000 (Smiths Detection, Herts, UK) and Russian built models. The requirement for a radioactive ionization source may limit their use.
Other analytical modalities are available. However, all such instruments can benefit from a portable “front end” device for sampling of vapors and particles associated with surfaces. In particular, there is a need for a front end device that can be directed to dislodge particles and residues from target surfaces and concentrate them before presentation to the analytical instrument of choice, an approach that optimizes sensitivity and can speed deployment because the need to enclose the target surface in a sealed chamber is avoided.
The preferred devices, systems and methods overcomes the above disadvantages and limitations and are portable and sensitive in detecting hazardous particles or vapors on the external surfaces of objects, structures, vehicles or persons.